Although, the basic concept of a fuel cell is quite simple, creating new designs and optimizing their performance takes serious work and a mastery of several technical areas. PEM Fuel Cell Modeling ...and Simulation Using Matlab, provides design engineers and researchers with a valuable tool for understanding and overcoming barriers to designing and building the next generation of PEM Fuel Cells. With this book, engineers can test components and verify designs in the development phase, saving both time and money. Easy to read and understand, this book provides design and modelling tips for fuel cell components such as: modelling proton exchange structure, catalyst layers, gas diffusion, fuel distribution structures, fuel cell stacks and fuel cell plant. This book includes design advice and MATLAB and FEMLAB codes for Fuel Cell types such as: polymer electrolyte, direct methanol and solid oxide fuel cells. This book also includes types for one, two and three dimensional modeling and two-phase flow phenomena and microfluidics.
Probability, Markov Chains, Queues, and Simulation provides a modern and authoritative treatment of the mathematical processes that underlie performance modeling. The detailed explanations of ...mathematical derivations and numerous illustrative examples make this textbook readily accessible to graduate and advanced undergraduate students taking courses in which stochastic processes play a fundamental role. The textbook is relevant to a wide variety of fields, including computer science, engineering, operations research, statistics, and mathematics.
The textbook looks at the fundamentals of probability theory, from the basic concepts of set-based probability, through probability distributions, to bounds, limit theorems, and the laws of large numbers. Discrete and continuous-time Markov chains are analyzed from a theoretical and computational point of view. Topics include the Chapman-Kolmogorov equations; irreducibility; the potential, fundamental, and reachability matrices; random walk problems; reversibility; renewal processes; and the numerical computation of stationary and transient distributions. The M/M/1 queue and its extensions to more general birth-death processes are analyzed in detail, as are queues with phase-type arrival and service processes. The M/G/1 and G/M/1 queues are solved using embedded Markov chains; the busy period, residual service time, and priority scheduling are treated. Open and closed queueing networks are analyzed. The final part of the book addresses the mathematical basis of simulation.
Each chapter of the textbook concludes with an extensive set of exercises. An instructor's solution manual, in which all exercises are completely worked out, is also available (to professors only).
Numerous examples illuminate the mathematical theories
Carefully detailed explanations of mathematical derivations guarantee a valuable pedagogical approach
Each chapter concludes with an extensive set of exercises
The sedimentation of anisotropically-shaped particles (discorectangles) was studied by means of Monte Carlo (MC) simulations in two-dimensional systems. The model with continuous positional and ...orientational degrees of freedom was considered. During sedimentation, the particle undergoes random translational and rotational Brownian motions and downward movements controlled by gravitation. Interrelation between gravitational and random motions was determined by the Péclet number varied in the interval Pe=0.05−0.2 (i.e. random walks were dominant). The value of particle aspect ratio (the length-to-width ratio) was varied in the interval ɛ=1.1−10. In the studied systems, the initial hindered sedimentation process was followed by a consolidation process at the bottom sediment. Studies revealed the complicated sedimentation-driven self-assembly, orientational ordering, and formation of stacks (tactoids) in sediment films. Permeability of sediment films was tested using the random walker method and was characterized by diffusion coefficient through the sediment film D. The evolution of the deposit height, order parameter, and diffusion coefficient D at different values of ɛ and Pe are discussed.
•Monte Carlo studies of sedimentation of discorectangles was performed.•The model accounts for continuous positional and orientational degrees of freedom.•The particle aspect ratio (the length-to-width ratio) was varied in the interval ɛ=1.1−10.•The complicated sedimentation-driven self-assembly and formation of tactoids was observed.•Permeability of sediment films was tested using the random walker method.
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Scientific simulation codes are public property sustained by the community. Modern technology allows anyone to join scientific software projects, from anywhere, remotely via the internet. The phonopy ...and phono3py codes are widely used open-source phonon calculation codes. This review describes a collection of computational methods and techniques implemented in these codes and shows their implementation strategies as a whole, aiming to be useful for the community. Some of the techniques presented here are not limited to phonon calculations and may therefore be useful in other areas of condensed matter physics.
Since the first light-emitting diode (LED) was invented by Holonyak and Bevacqua in 1962, LEDs have made remarkable progress in the past few decades with the rapid development of epitaxy growth, chip ...design and manufacture, packaging structure, processes, and packaging materials. LEDs have superior characteristics such as high efficiency, small size, long life, low power consumption, and high reliability. The market for white LED is growing rapidly in various applications. It has been widely accepted that white LEDs will be the fourth illumination source to substitute the incandescent, fluorescent, and high-pressure sodium lamps. With the development of LED chip and packaging technologies, the efficiency of high power white LED will broaden the application markets of LEDs while changing the lighting concepts of our lives.In LED Packaging for Lighting Applications, Professors Liu and Luo cover the full spectrum of design, manufacturing, and testing. Many concepts are proposed for the first time, and readers will benefit from the concurrent engineering and co-design approaches to advanced engineering design of LED products.One of the only books to cover LEDs from package design to manufacturing to testingFocuses on the design of LED packaging and its applications such as road lightsIncludes design methods and experiences necessary for LED engineers, especially optical and thermal designIntroduces novel LED packaging structures and manufacturing processes, such as ASLPCovers reliability considerations, the most challenging problem for the LED industryProvides measurement and testing standards, which are critical for LED development, for both LED and LED fixturesCodes and demonstrations available from the book’s Companion WebsiteThis book is ideal for practicing engineers working in design or packaging at LED companies and graduate students preparing for work in industry. This book also provides a helpful introduction for advanced undergraduates, graduates, researchers, lighting designers, and product managers interested in the fundamentals of LED design and production.Color version of selected figures can be found at www.wiley.com/go/liu/led
As an effective model corresponding to Z3-symmetric QCD (Z3-QCD), we construct a Z3-symmetric effective Polyakov-line model (Z3-EPLM) by using the logarithmic fermion effective action. Since Z3-QCD ...tends to QCD in the zero-temperature limit, Z3-EPLM also agrees with the ordinary effective Polyakov-line model (EPLM) there; note that (ordinary) EPLM does not possess Z3 symmetry. Our main purpose is to discuss a sign problem appearing in Z3-EPLM. The action of Z3-EPLM is real when not only the Polyakov line is real but also its Z3 images. This suggests that the sign problem becomes milder in Z3-EPLM than in EPLM. In order to confirm this suggestion, we do lattice simulations for both EPLM and Z3-EPLM by using the reweighting method with the phase quenched approximation. In the low-temperature region, the sign problem is milder in Z3-EPLM than in EPLM. We also propose a new reweighting method. This makes the sign problem very weak in Z3-EPLM.
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Modern simulation techniques have reached a level of maturity which allows a wide range of problems in chemistry and materials science to be addressed. Unfortunately, the application of first ...principles methods with predictive power is still limited to rather small systems, and despite the rapid evolution of computer hardware no fundamental change in this situation can be expected. Consequently, the development of more efficient but equally reliable atomistic potentials to reach an atomic level understanding of complex systems has received considerable attention in recent years. A promising new development has been the introduction of machine learning (ML) methods to describe the atomic interactions. Once trained with electronic structure data, ML potentials can accelerate computer simulations by several orders of magnitude, while preserving quantum mechanical accuracy. This Review considers the methodology of an important class of ML potentials that employs artificial neural networks.
Potential energy surfaces: A new class of interatomic potentials has emerged in recent years employing machine learning (ML) techniques. These potentials combine the accuracy of first principles methods with the efficiency of simple classical force fields. This Review discusses the methodology of an important class of ML potentials that makes use of artificial neural networks and is applicable to complex systems.
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